In recent years, as information processing systems for which high reliability is demanded, an information processing system has been known in which, in order to increase the failure tolerance, control devices including hardware, such as a processor, are provided redundantly and both the control devices are caused to perform information processing. Such an information processing system has a function of continuing information processing using an input/output signal to a backup control device that is operating normally even when an error occurs in a control device that is being used as an active control device.
Japanese Laid-open Patent Publication No. 62-191299 discloses an example of a related art.